How reproduce a real led lamp with IES photometric data?
The first bit of info you need is that in Cycles, the emission unit of light is Irradiance (or Radiance Flux), it is in watts per square meter.

You can read how that corresponds to Lux (in lumen) here: What kind of units does the Cycles emission strength use?
The second bit is that you can import IES files into Blender through this addon. It will create a light with rig that you can control to for example set direction of the lamp.

This light uses mapping vectors and a custom Curve (that is imported from the IES file) to influence the strength of light based on emission direction:



The tricky bit is that the imported light type is Point, so you are getting only the emission of light, but not the light surface itself. You will have to fake the light's glass cover with translucent shader, that does not effect the light from the Point light - for camera ray it will be translucent, for light it must be completely transparent.
The third bit of puzzle is that you get the color from black body radiation node:



Note that in sRGB color space the white point is at 6500K, so you might want to compensate for that.